The epidemiology of function, especially among the elderly and the oldest old is largely unstudied, particularly with representative samples of the elderly. The NHANES III survey with its commitment to sampling the elderly and to following the cohort, represents a unique opportunity for study. Physical function can be measured in a variety of ways: from self-report to observe functioning of actual daily activities. To permit efficient measurement of function in the elderly population, reliability of various techniques by expanding the continuum from a screening functional test to observed physical performance needs to be established. This proposal will develop instruments expanding this range for population studies in convenient samples of elderly living in the community in rural and urban areas and to do a one-year followup of the group. The emphasis of the sample is on those 65 and older and will also include a number of subjects over 75 years of age. The statistical properties of such measures will be established and hypotheses relating function to various care outcomes will be evaluated.